When hard materials such as natural stone, concrete and the like are to be cut or drilled, circular saws, gang saws or annular bits are used, the cutting edge of the tools being provided with diamond-impregnated segments or coatings. After use of the tool for cutting, the cutting edges of the tools become rounded due to the wear. This rounded cutting edge enlarges the surface that is in contact with the work piece, thereby increasing the power demands on the cutting machine and the blade that carries the cutting segments. Also, the rounded cutting edge leads to a lateral squeezing of the segment which puts great pressure on the segment. This increased pressure yields a poor quality cut, and causes portions of the segment to be broken off. Since the cutting segment needs to remain thick enough to provide a good kerf through the material, the breaking off of the sides of the segment renders the segment no longer usable.
Previous efforts at solving the above noted problems have included the use of various shapes of segments in an effort to cause the desired wear pattern on the segment, but these have been very expensive to produce, and many of the designs still tend to become rounded and are subject to the above stated difficulties. Another prior art effort at solving the problems has been to make the segment in layers, with the outer edges of the segment containing more diamond, or different sizes and qualities of diamond. Again, these segments are much more expensive to manufacture, and still do not wear precisely as desired.